Lumbreras B, Pascual E, Frasquet J, González-Salinas J, Rodríguez E, Hernández-Aguado I
Department of Clinical Analysis, Hospital General Universitario de Alicante, Spain.
Ann Rheum Dis. 2005 Apr;64(4):612-5. doi: 10.1136/ard.2004.027268.
Identification of monosodium urate (MSU) and calcium pyrophosphate dehydrate (CPPD) crystals in synovial fluid samples is diagnostic of gout and CPPD crystal related arthropathy. Various studies have shown poor consistency in results of crystal analysis.
To determine whether training of the analysts increases the consistency.
An expert rheumatologist gave a course on crystal detection and identification. The four trained observers then blindly and independently examined synovial fluid samples previously classified by the expert which had been obtained from patients with both crystal arthropathies and other non-crystal related inflammatory joint conditions.
194 observations were made on 64 synovial fluid samples: 96 without crystals (49.4%), 55 with CPPD crystal (28.4%), and 43 with MSU crystals (22.2%). For crystal detection (presence or absence of crystals), sensitivity was 95.9% and specificity 86.5%. For identification of MSU crystals, sensitivity was 95.3% and specificity 97.2%. For identification of CPPD crystals, sensitivity was 92.7% and specificity 92.1%. The kappa index of agreement with the reference standard between the observers was 0.84 for any crystal detection, 0.93 for MSU crystal sample identification, and 0.79 for CPPD crystal sample identification.
For trained observers, the detection and identification of crystals in synovial fluid is a consistent procedure.
滑膜液样本中尿酸钠(MSU)和焦磷酸钙二水合物(CPPD)晶体的鉴定可诊断痛风和与CPPD晶体相关的关节病。多项研究表明晶体分析结果的一致性较差。
确定分析人员的培训是否能提高一致性。
一位专家级风湿病学家开设了晶体检测与鉴定课程。然后,四名经过培训的观察者对专家先前分类的滑膜液样本进行盲法独立检查,这些样本取自患有晶体关节病和其他非晶体相关炎性关节疾病的患者。
对64个滑膜液样本进行了194次观察:96个无晶体(49.4%),55个有CPPD晶体(28.4%),43个有MSU晶体(22.2%)。对于晶体检测(有无晶体),敏感性为95.9%,特异性为86.5%。对于MSU晶体的鉴定,敏感性为95.3%,特异性为97.2%。对于CPPD晶体的鉴定,敏感性为92.7%,特异性为92.1%。观察者与参考标准之间的一致性kappa指数在任何晶体检测时为0.84,在MSU晶体样本鉴定时为0.93,在CPPD晶体样本鉴定时为0.79。
对于经过培训的观察者,滑膜液中晶体的检测和鉴定是一个一致的过程。